﻿using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace MyTest
{
    /// <summary>
    /// 教员:薛海
    /// 微信:xuehai03
    /// QQ:289477003
    /// 验证码示例
    /// 2019-2-20
    /// </summary>
    public partial class frmNum : Form
    {
        public frmNum()
        {
            InitializeComponent();
            UpdateVerifyCode();
        }

        //验证码的长度
        private const int iVerifyCodeLength = 6;
        //随机码
        private String strVerifyCode = "";

        //更新验证码
        private void UpdateVerifyCode()
        {
            strVerifyCode = CreateRandomCode(iVerifyCodeLength);
            CreateImage(strVerifyCode);
        }

        //创建随机数
        private string CreateRandomCode(int iLength)
        {
            int rand;
            char code;
            string randomCode = String.Empty;

            //生成一定长度的验证码
            System.Random random = new Random();
            for (int i = 0; i < iLength; i++)
            {
                rand = random.Next();

                if (rand % 3 == 0)
                {
                    code = (char)('A' + (char)(rand % 26));
                }
                else
                {
                    code = (char)('0' + (char)(rand % 10));
                }

                randomCode += code.ToString();
            }
            return randomCode;
        }

        ///  创建随机码图片
        private void CreateImage(string strVerifyCode)
        {
            try
            {
                int iRandAngle = 45;    //随机转动角度
                int iMapWidth = (int)(strVerifyCode.Length * 21);
                Bitmap map = new Bitmap(iMapWidth, 28);     //创建图片背景

                Graphics graph = Graphics.FromImage(map);
                graph.Clear(Color.AliceBlue);//清除画面，填充背景
                graph.DrawRectangle(new Pen(Color.Black, 0), 0, 0, map.Width - 1, map.Height - 1);//画一个边框
                graph.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;//模式


                Random rand = new Random();

                //背景噪点生成
                Pen blackPen = new Pen(Color.LightGray, 0);
                for (int i = 0; i < 50; i++)
                {
                    int x = rand.Next(0, map.Width);
                    int y = rand.Next(0, map.Height);
                    graph.DrawRectangle(blackPen, x, y, 1, 1);
                }


                //验证码旋转，防止机器识别
                char[] chars = strVerifyCode.ToCharArray();//拆散字符串成单字符数组

                //文字距中
                StringFormat format = new StringFormat(StringFormatFlags.NoClip);
                format.Alignment = StringAlignment.Center;
                format.LineAlignment = StringAlignment.Center;

                //定义颜色
                Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };
                //定义字体
                string[] font = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };

                for (int i = 0; i < chars.Length; i++)
                {
                    int cindex = rand.Next(7);
                    int findex = rand.Next(5);
                    //字体
                    Font f = new System.Drawing.Font(font[findex], 13, System.Drawing.FontStyle.Bold);//字体样式(参数2为字体大小)
                    Brush b = new System.Drawing.SolidBrush(c[cindex]);

                    Point dot = new Point(16, 16);

                    float angle = rand.Next(-iRandAngle, iRandAngle);//转动的度数

                    graph.TranslateTransform(dot.X, dot.Y);//移动光标到指定位置
                    graph.RotateTransform(angle);
                    graph.DrawString(chars[i].ToString(), f, b, 1, 1, format);

                    graph.RotateTransform(-angle);//转回去
                    graph.TranslateTransform(2, -dot.Y);//移动光标到指定位置
                }
                this.pictureBox1.Image = map;

            }
            catch (ArgumentException)
            {
                MessageBox.Show("创建图片错误。");
            }
        }

        //看不清  换一张
        private void button1_Click(object sender, EventArgs e)
        {
            UpdateVerifyCode();
        }

        //验证是否匹配
        private void btnOk_Click(object sender, EventArgs e)
        {
            if (this.txtNum.Text.Trim().Equals(strVerifyCode))
            {
                MessageBox.Show("匹配成功");
            }
            else
            {
                MessageBox.Show("验证码不正确");
            }
        }
    }
}
